What about the Yamaha wr450f? That is only 450cc yet it puts out damn near 60hp: http://www.motorcyclespecs.co.za/model/yamaha/yamaha_wr450f 03.htm That is a 2003 model as well so it's not massively cutting edge. Also I wanted to revisit this thread to ask was it ever determined whether the 610 was 45 RWHP or 45 BHP? Because 45 BHP would be pitiful... Another thing, from reading car and motorbike forums over the years it appears that carbs are easy to tune for more power. So enough of all of this new school JD Power tuner BS, how can I tune the 610's DelLorto carburettor for more power? I have read about changing jet needles but before I do that I know I can adjust the mixture screw. The manual doesn't say anything about the mixture screw in the "settings and adjustments" section: Also what's the deal with the spark plug gap? I have searched on here but no threads come up on that, I have a healthy spark but the gap is around 4.5mm, not the 6-7mm that the manual recommends. I am gonna pull the plug and have a look at it's condition.
You should already know that an engine is basically just an air pump. The fuel used is limited by how much air your engine can pump and that limits how much power can be made. Im sorry if im telling you how to suck eggs, its just not as simple as add more fuel - get more power, unless your fueling is already poorly tuned Youve got to find a way of moving more air - hotter cams, higher revs, more ccs, bigger valves, flowed head, maybe even forced induction - http://www.cafehusky.com/threads/my-sm-610-ie-with-some-more.78634/#post-509881
